[tor-dev] Proposal: Merging Hidden Service Directories and Introduction Points
john.brooks at dereferenced.net
Mon Jul 13 18:10:03 UTC 2015
teor <teor2345 at gmail.com> wrote:
>> On 13 Jul 2015, at 07:48 , John Brooks <john.brooks at dereferenced.net>
>> 4.2. Restriction on the number of intro points and impact on load
>> One drawback of this proposal is that the number of introduction points
>> of a
>> hidden service is now a constant global parameter. Hence, a hidden
>> can no longer adjust how many introduction points it uses, or select
>> nodes that will serve as its introduction points.
> If we decide we want to allow popular hidden services to have more than 6
> introduction points, we could use some of the 4 extra bits in the address
> to encode an introduction point count multiplier.
Interesting approach. This value would be difficult to change on an existing
service, because it would have to hand out a new subtly-different URL to all
clients. We had also briefly discussed using the extra 4 bits as a checksum
on the address.
> I can see advantages in popular, high-availability, or politically
> unpopular hidden services having more introduction points. It would make
> it harder to overload all the introduction points, particularly once the
> server can't change introduction points when they go down.
I _think_ that 6 introduction points can handle a lot of traffic, and I
think it’s mostly sufficient for reliability and abuse-resistance.
Personally, I’d like to see statistics showing that introduction points are
a bottleneck before we design systems to increase the number of them. I
suspect that guards fall down long before introduction points do. There are
tradeoffs to using more, both in terms of network load and privacy (e.g.
exposing popularity to relays).
> Perhaps we only need two introduction point counts: 6 and 6n, where n is
> initially chosen based on the most popular hidden services, and is a
> consensus parameter, so can be updated if needed.
The introduction point count should be a consensus parameter; 224 was going
to do this for HSDirs already.
> Tim Wilson-Brown (teor)
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